THE MARINE ALG.E OF NEW ENGLAND. 1G5 



l>onie in parallel rows. Such collections of tetiaspores are called stieliidia. The 

 fronds in the present suhonler vary ;n^\Uly. In the more beautiful genera of tropical 

 re«;ions they are in the form of complicated net-works or in membranes in which the 

 cells are arran<;e«l in re«jular order, but in th«' majority of the j;jeuera the fronds are 

 liliform and branching; an<l <xenerally beset, at h>ast at some seasons, with delieate 

 hairs. In most of the genera representetl on our coast tlu' fronds hav«> a polysii)lionou.s 

 axis, that is, on cross-s»'ction there is si-en tt) be a central cell surrouudr*! by a circb' 

 of lar«;e cells, and in lon<;itUilinal sections there is a central lilainent coniposed of lar<it' 

 cells, and on eaeh side a lateral lilament whose cells rorrespond in len^xth to those of 

 the central hlament, the ui)p«'i- and lowi-r walls t)f the three cells foruiiii^ two i>arallel 

 lines. 



Fix)iuls thittoiR'il OdonthaUa. 



Fronds tilitbrm 1 



1. Tvtrasporos borno in the smalK'r branches L' 



Tetraspoivs borne in .stichidia -4 



2. Superficial cells small, irregularly placed 3 



Superficial cells, at least in the younger branches, in transverse 



bands rolysiphonia, 



3. Branches filitbrni throughout Bhodomela, 



Ultimate branches club-shaped, much attenuated at hase . Chondriojysis. 



4. Fronds beset with monosiphonons branchlets Dasija. 



Fronds without monosiphonons branchlets, superficial cells quad- 

 rate Bostrych ia. 



CUOXDEIOPSIS, J. Ag. 



(From xovci)oc, cartilage, and oj.'/f, an api)earance.) 



Fronds brownish red, terete or subcomiiressed, pinnately decomi)ound, 

 branches virgate, much constricted at the base, composed of a monosi- 

 phonous axis surrounded by a few (4-G) siphons and surrounded by sec- 

 ondary siphons, cortex of small i>olygonal cells; antheridia borne in 

 short disk-like branchlets covering both surlaces except at the margin; 

 tetraspores tripartite, in club-shai^ed branchlets ; cystocarps sessile, 

 ovate, with a distinct carpostome, spores pyriform, on short pedicels 

 from a basal placenta. 



A penus of which about twenty species have been described, which inhabit princi- 

 pally the warmer parts of the world, some being wi4h'ly dilfused. They are as a whole 

 dithcult to distinguish, the specific marks being principally the ramification and shape 

 of the branchlets, points in which the ditVerent species vary very nnich. The anther- 

 idia are very peculiar. On the upper branches are home llattened, more or less in- 

 eurvetl, disk-shaped branches, whoso margin is wavy. The antheridia cover both 

 -ides of these discoidal branches, except at the margin, which is composed of largo 

 liyaline cells. The fronds are iutennediato between those of lihodomela and Laurencia, 

 and the branchlets are always much constricted at the ba.se. Most of the si>ecies were 

 formerly included by Lamouroux and others in the genus Laurviuia. By C. A. Agardh 

 they were, in the Species Algarum, placed in Chondria, a genus retained by IIar\-ey in the 

 Nereis. Since as originally defined the genus Chondria embraced alg;e of rather remote 

 relationship to one another, J. G. Agardh, in the third volume of his Species Algarum, 

 separated the present group, under the name of Chondriopsis, the name Chondria being 



